Linear LT3995 Quick setup guide

dc1832af

DEMO MANUAL DC1832A

Description

LT3995

60V, 3A, 2MHz Step-Down

Switching Regulator with

2.7µA Quiescent Current

Demonstration circuit 1832A is a monolithic step-down

DC/DC switching regulator featuring the LT3995. The

LT3995isacompact,highefficiencymonolithicstep-down

switching regulator thatconsumes only2.7μAofquiescent

current. The demo circuit is designed for 3.3V, 3A output

from a 4.3V to 60V input. The switching frequency can be

programmed either via oscillator resistor or external clock

up to 2MHz. To synchronize to an external clock, move

JP2 to SYNC and apply the external clock to the SYNC

turret. The RT resistor (R5) should be chosen to set the

LT3995 internal switching frequency at least 20% below

the lowest synchronization input frequency.

Low ripple Burst Mode

operation increases the effi-

ciency at the light load while keeping the output ripple

below15mV.The SYNC pin on the demo board is grounded

by default by setting JP2 at RT FREQ for low ripple

Burst Mode operation. Figure1 shows the demo board

efficiency at 12V input voltage.

The LT3995 is in shutdown when the EN pin is low and

active when the pin is high. The threshold of the EN pin

is accurate at 1.02V with 60mV of hysteresis. Users can

populate R7 and R8 to provide a programmable under L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered

trademarks of Linear Technology Corporation. All other trademarks are the property of their

respective owners.

voltage lockout. A low dropout voltage of 500mV is main-

tainedwhentheinputvoltagedropsbelowtheprogrammed

output voltage. During a short-circuit fault, the LT3995

has current limit foldback to limit the power dissipation.

The demo board has an EMI filter installed. The EMI

performance of the demo board at 12V input voltage is

shown on Figure 2. The limit in Figure 2 is EN55022 Class

B. The figure shows the circuit passes the test with a wide

margin. To use the EMI filter, the input should be tied to

VEMI not VIN.

The LT3995 data sheet gives a complete description of

the part, operation and application information. The data

sheet must be read in conjunction with this demo manual

for demo circuit 1832A. The LT3995 is assembled in a 16-

lead plastic MSOP package with an exposed pad for low

thermal resistance. Proper board layout is essential for

bothproperoperationandmaximumthermalperformance.

See the data sheet sections for details.

Design files for this circuit board are available at

http://www.linear.com/demo

Figure 1. LT3995 Efficiency vs Load Current,

12VIN to 3.3VOUT Efficiency

Figure 2. LT3995 Demo Board EMI Performance

(Switching Frequency = 300kHz, VIN = 12V)

LOAD CURRENT (A)

EFFICIENCY (%)

dc1832a F01

0.5 11.5 2 2.5

10dB/DIV LOG, REF 70.00dBµV

dc1832a F02

START 150kHz

RES BW (CISPR) 9kHz

TRACE 1 PASS

–30

–10

VBW 62kHz

–20

STOP 30.00 MHz

SWEEP 717ms (6637pts)

dc1832af

DEMO MANUAL DC1832A

Quick start proceDure

Demonstration circuit 1832A is easy to set up to evalu-

ate the performance of the LT3995. Refer to Figure 3

for proper measurement equipment setup and use the

following procedure.

NOTE. When measuring the input or output voltage ripple,

care must be taken to avoid a long ground lead on the

oscilloscope probe. Measure the input or output voltage

ripple by touching the probe tip directly across the VIN

or VOUT and GND terminals. See Figure 4 for the proper

scope technique.

1. Place JP1 on the ON position.

2. Place JP2 on the RT FREQ position.

3. With power off, connect the input power supply to VIN

and GND. Make sure that the input voltage does not

exceed 60V.

4. With power off, connect load from VOUT to GND.

5. Turn on the power at the input.

6. Check for the proper output voltage (3.3V).

NOTE. If there is no output, temporarily disconnect the

load to make sure that the load is not set too high or

is shorted.

7. Once the proper output voltage is established, adjust

the load within the operating ranges and observe the

output voltage regulation, ripple voltage, efﬁciency and

other parameters.

8. An external clock can be added to the SYNC terminal

when SYNC function is used (JP2 on the SYNC posi-

tion). Please make sure that the SYNC frequency is at

least 20% higher than the set switching frequency.

See the data sheet Synchronization section.

performance summary

PARAMETER CONDITIONS VALUE

Guaranteed Minimum Input Voltage 4.3V

Maximum Input Voltage 60V

Output Voltage VOUT VIN = 4.3V ~ 60V 3.275V ± 3%

Switching Frequency RT= 182k 300kHz ± 20%

Guaranteed Maximum Output Current IOUT VIN = 4.3V ~ 60V 3A

Typical Efficiency VIN = 12V, IOUT = 3A 82.2%

Typical Output Voltage Ripple VIN = 12V, IOUT = 3A 11mV

Specifications are at TA= 25°C

dc1832af

DEMO MANUAL DC1832A

Figure 3. Proper Measurement Equipment Setup

Figure 4. Measuring Input or Output Ripple

Quick start proceDure

dc1832af

DEMO MANUAL DC1832A

parts List

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 2 C1, C8 CAP., X5R, 47µF, 10V, 20%, 1210 TDK, C3225X5R1A476M

2 1 C2 CAP., X5R, 0.47µF, 25V, 10%, 0603 TDK, C1608X5R1E474M

3 2 C3, C7 CAP., X7R, 2.2µF, 100V, 10%,1210 TDK, C3225X7R2A225M

4 1 C5 CAP., C0G, 10pF, 50V, 10%, 0402 TDK, C1005C0G1H100D

5 1 C6 CAP., X7R, 10nF, 25V, 10%, 0402 TDK, C1005X7R1E103K

6 1 C11 CAP., X5R, 1µF, 10V, 10%, 0603 TDK, C1608X5R1A105K

7 1 C12 CAP., X7R, 0.1µF, 100V, 10%, 0603 MURATA, GRM188R72A104KA35D

8 1 D1 DIODE, PDS360 PowerDi5 DIODE INC., PDS360

9 1 L1 IND, 8.2µH COILCRAFT, XAL6060-822ME

10 1 R1 RES., CHIP, 1.00M, 1/16W, 1%, 0402 NIC, NRC04F1004TRF

11 1 R2 RES., CHIP, 576k, 1/16W, 1%, 0402 NIC, NRC04F5763TRF

12 1 R5 RES., CHIP, 182k, 1/16W, 1%, 0402 NIC, NRC04F1823TRF

13 1 R6 RES., CHIP, 200k, 1/16W, 1%, 0402 NIC, NRC04F2003TRF

14 1 U1 I.C., LT3995EMSE, MSE16 LINEAR TECHNOLOGY, LT3995EMSE

Additional Demo Board Circuit Components

1 1 C4 CAP., ALUM., 100µF, 100V, 10% SUN ELECT, 100CE100KXT

2 2 C9, C10 CAP., X7R, 2.2µF, 100V, 10%, 1210 TDK, C3225X7R2A225M

3 1 C13 CAP., HVP SERIES, 33µF, 63V, 20% SUNCON, 63HVP33M

4 1 L2 IND, 1.0µH VISHAY, IHLP-1616BZER1R0M01

5 1 L3 IND, 3.3µH VISHAY, IHLP-2020BZER3R3M01

6 0 R7,R8 RES., 0603 OPT

Hardware: For Demo Board Only

1 7 E1, E2, E3, E4, E5, E6, E7 TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0

2 2 E8, E9 TESTPOINT, TURRET, 0.061" PBF MILL-MAX, 2308-2-00-80-00-00-07-0

3 2 JP1, JP2 JMP, 1X3-079 SAMTEC, TMM-103-02-L-S

4 2 XJP1, XJP2 SHUNT, 2mm CTRS. SAMTEC, 2SN-BK-G

dc1832af

DEMO MANUAL DC1832A

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

schematic Diagram

NOTE: UNLESS OTHERWISE SPECIFIED

SUNCON

100CE100KXT

ALL CAPACITORS ARE IN MICROFARADS, 0402.

1. ALL RESISTORS ARE IN OHMS, 0402.

VIN

VOUT

JP2

SYNC

RT FREQ

JP2

SYNC

RT FREQ

PDS360

2 1

2.2uF

100V

1210

2.2uF

100V

1210

C10

2.2uF

100V

1210

C10

2.2uF

100V

1210

EN/UVLO

100uF

100V

100uF

100V

2.2uF

100V

1210

2.2uF

100V

1210

10nF

OPT

0603

OPT

0603

182k

(300kHz)

182k

(300kHz)

GND E4

GND

C11

1uF

0603

10V

C11

1uF

0603

10V

VIN

4.3V - 60V E3

VIN

4.3V - 60V

1.0uH

IND-IHLP1616BZ-01

1.0uH

IND-IHLP1616BZ-01

0.47uF

0603

0.47uF

0603

E2 GND

200K

VEMI

2.2uF

100V

1210

2.2uF

100V

1210

LT3995EMSE

OUT 3

FB 1

VIN

BOOST 4

SW 5

SYNC 16

GND

VIN

11 VIN

SW 6

SW 7

RT 14

JP1

OFF

JP1

OFF

GND

E7 SYNC

576k

OPT

0603

OPT

0603

C13

33uF

63V

63HVP33

C13

33uF

63V

63HVP33

VOUT

3.3V / 3A

VOUT

3.3V / 3A

8.2uH

47uF

10V

1210

47uF

10V

1210

1.00M

3.3uH

IND-IHLP2020BZ-01

3.3uH

IND-IHLP2020BZ-01

47uF

10V

1210

47uF

10V

1210

10pF

C12

0.1uF

0603

100V

C12

0.1uF

0603

100V

dc1832af

DEMO MANUAL DC1832A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com

 LINEAR TECHNOLOGY CORPORATION 2013

LT 0513 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LT C ) provides the enclosed product(s) under the following AS IS conditions:

This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT

OR EVALUATION PURPOSES ONLY and is not provided by LT C for commercial use. As such, the DEMO BOARD herein may not be complete

in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety

measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union

directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.

If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date

of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU

OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS

FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR

ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LT C from all claims

arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all

appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or

agency certified (FCC, UL, CE, etc.).

No License is granted under any patent right or other intellectual property whatsoever. LT C assumes no liability for applications assistance,

customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

LT C currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.

Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and

observe good laboratory practice standards. Common sense is encouraged.

This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LT C applica-

tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

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